Antihistamine–decongestant combinations are often used to treat subjects with SAR; however, data for such combinations are limited. Therefore, the onset-of-action data from two recent studies investigating the efficacy and safety of fexofenadine HCl 60 mg/pseudoephedrine HCl 120 mg (FEX/PSE) in patients with moderate-to-severe SAR to ragweed pollen were pooled.

Two single-center, single-dose, randomized, double-blind, placebo-controlled, parallel-group studies were performed in the Atlanta allergen exposure unit (AEU). Patients qualifying on screening were exposed to allergen for 6 hours, and recorded their symptoms using diary cards at 15-minute intervals up to 2 hours post-dose, then at 30-minute intervals for the remaining 4 hours. The Major Symptom Complex (MSC) score consisted of the sum of sneezing, itchy nose, runny nose, watery eyes, itchy eyes, itchy ears/throat and stuffy nose individual scores. Onset of action was defined as the first time that two consecutive, statistically significant absolute changes in MSC score from baseline were achieved for study drug relative to placebo.

Of 1693 subjects screened, 784 were randomized; 391 to FEX/PSE and 393 to placebo. The onset of action of FEX/PSE in patients with moderate-to-severe SAR to ragweed pollen was 45 minutes (p=0.0045 versus placebo; ITT population). Reductions in absolute MSC scores were significantly greater with FEX/PSE compared with placebo at all subsequent time-points (to 6 hours post-dose; p<0.0001).

The results of two pooled studies conducted in a controlled AEU environment demonstrate that FEX/PSE has an onset of action of 45 minutes in patients with moderate-to-severe SAR to ragweed pollen.